package general.feature_extractors;
/*
    
       Porter stemmer in Java. The original paper is in
    
           Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
           no. 3, pp 130-137,
    
       See also http://www.tartarus.org/~martin/PorterStemmer
    
       History:
    
       Release 1
    
       Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
       The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
       is then out outside the bounds of b.
    
       Release 2
    
       Similarly,
    
       Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
       'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
       b[j] is then outside the bounds of b.
    
       Release 3
    
       Considerably revised 4/9/00 in the light of many helpful suggestions
       from Brian Goetz of Quiotix Corporation (brian@quiotix.com).
    
       Release 4
    
    */
    
    import java.io.*;
    
    /**
      * Stemmer, implementing the Porter Stemming Algorithm
      *
      * The Stemmer class transforms a word into its root form.  The input
      * word can be provided a character at time (by calling add()), or at once
      * by calling one of the various stem(something) methods.
      */
    
public class Stemmer
    {  private char[] b;
       private int i,     /* offset into b */
                   i_end, /* offset to end of stemmed word */
                   j, k;
       private static final int INC = 50;
                         /* unit of size whereby b is increased */
       public Stemmer()
       {  b = new char[INC];
          i = 0;
          i_end = 0;
       }

       public static String stem( String word ) {
    	   Stemmer s = new Stemmer();
    	   s.add(word.toCharArray(),word.length());
    	   s.stem();
    	   return new String(s.getResultBuffer());
       }
       
       /**
        * Add a character to the word being stemmed.  When you are finished
        * adding characters, you can call stem(void) to stem the word.
        */
    
       public void add(char ch)
       {  if (i == b.length)
          {  char[] new_b = new char[i+INC];
             for (int c = 0; c < i; c++) new_b[c] = b[c];
             b = new_b;
          }
          b[i++] = ch;
       }
    
    
       /** Adds wLen characters to the word being stemmed contained in a portion
        * of a char[] array. This is like repeated calls of add(char ch), but
        * faster.
        */
    
       public void add(char[] w, int wLen)
       {  if (i+wLen >= b.length)
          {  char[] new_b = new char[i+wLen+INC];
             for (int c = 0; c < i; c++) new_b[c] = b[c];
             b = new_b;
          }
          for (int c = 0; c < wLen; c++) b[i++] = w[c];
       }
    
       /**
        * After a word has been stemmed, it can be retrieved by toString(),
        * or a reference to the internal buffer can be retrieved by getResultBuffer
        * and getResultLength (which is generally more efficient.)
        */
       public String toString() { return new String(b,0,i_end); }
    
       /**
        * Returns the length of the word resulting from the stemming process.
        */
       public int getResultLength() { return i_end; }
    
       /**
        * Returns a reference to a character buffer containing the results of
        * the stemming process.  You also need to consult getResultLength()
        * to determine the length of the result.
        */
       public char[] getResultBuffer() { return b; }
    
       /* cons(i) is true <=> b[i] is a consonant. */
    
       private final boolean cons(int i)
       {  switch (b[i])
          {  case 'a': case 'e': case 'i': case 'o': case 'u': return false;
             case 'y': return (i==0) ? true : !cons(i-1);
             default: return true;
          }
       }
    
       /* m() measures the number of consonant sequences between 0 and j. if c is
          a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
          presence,
    
             <c><v>       gives 0
             <c>vc<v>     gives 1
             <c>vcvc<v>   gives 2
             <c>vcvcvc<v> gives 3
             ....
       */
    
       private final int m()
       {  int n = 0;
          int i = 0;
          while(true)
          {  if (i > j) return n;
             if (! cons(i)) break; i++;
          }
          i++;
          while(true)
          {  while(true)
             {  if (i > j) return n;
                   if (cons(i)) break;
                   i++;
             }
             i++;
             n++;
             while(true)
             {  if (i > j) return n;
                if (! cons(i)) break;
                i++;
             }
             i++;
           }
       }
    
       /* vowelinstem() is true <=> 0,...j contains a vowel */
    
       private final boolean vowelinstem()
       {  int i; for (i = 0; i <= j; i++) if (! cons(i)) return true;
          return false;
       }
    
       /* doublec(j) is true <=> j,(j-1) contain a double consonant. */
    
       private final boolean doublec(int j)
       {  if (j < 1) return false;
          if (b[j] != b[j-1]) return false;
          return cons(j);
       }
    
       /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
          and also if the second c is not w,x or y. this is used when trying to
          restore an e at the end of a short word. e.g.
    
             cav(e), lov(e), hop(e), crim(e), but
             snow, box, tray.
    
       */
    
       private final boolean cvc(int i)
       {  if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2)) return false;
          {  int ch = b[i];
             if (ch == 'w' || ch == 'x' || ch == 'y') return false;
          }
          return true;
       }
    
       private final boolean ends(String s)
       {  int l = s.length();
          int o = k-l+1;
          if (o < 0) return false;
          for (int i = 0; i < l; i++) if (b[o+i] != s.charAt(i)) return false;
          j = k-l;
          return true;
       }
    
       /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
          k. */
    
       private final void setto(String s)
       {  int l = s.length();
          int o = j+1;
          for (int i = 0; i < l; i++) b[o+i] = s.charAt(i);
          k = j+l;
       }
    
       /* r(s) is used further down. */
    
       private final void r(String s) { if (m() > 0) setto(s); }
    
       /* step1() gets rid of plurals and -ed or -ing. e.g.
    
              caresses  ->  caress
              ponies    ->  poni
              ties      ->  ti
              caress    ->  caress
              cats      ->  cat
    
              feed      ->  feed
              agreed    ->  agree
              disabled  ->  disable
    
              matting   ->  mat
              mating    ->  mate
              meeting   ->  meet
              milling   ->  mill
              messing   ->  mess
    
              meetings  ->  meet
    
       */
    
       private final void step1()
       {  if (b[k] == 's')
          {  if (ends("sses")) k -= 2; else
             if (ends("ies")) setto("i"); else
             if (b[k-1] != 's') k--;
          }
          if (ends("eed")) { if (m() > 0) k--; } else
          if ((ends("ed") || ends("ing")) && vowelinstem())
          {  k = j;
             if (ends("at")) setto("ate"); else
             if (ends("bl")) setto("ble"); else
             if (ends("iz")) setto("ize"); else
             if (doublec(k))
             {  k--;
                {  int ch = b[k];
                   if (ch == 'l' || ch == 's' || ch == 'z') k++;
                }
             }
             else if (m() == 1 && cvc(k)) setto("e");
         }
       }
    
       /* step2() turns terminal y to i when there is another vowel in the stem. */
    
       private final void step2() { if (ends("y") && vowelinstem()) b[k] = 'i'; }
    
       /* step3() maps double suffices to single ones. so -ization ( = -ize plus
          -ation) maps to -ize etc. note that the string before the suffix must give
          m() > 0. */
    
       private final void step3() { if (k == 0) return; /* For Bug 1 */ switch (b[k-1])
       {
           case 'a': if (ends("ational")) { r("ate"); break; }
                     if (ends("tional")) { r("tion"); break; }
                     break;
           case 'c': if (ends("enci")) { r("ence"); break; }
                     if (ends("anci")) { r("ance"); break; }
                     break;
           case 'e': if (ends("izer")) { r("ize"); break; }
                     break;
           case 'l': if (ends("bli")) { r("ble"); break; }
                     if (ends("alli")) { r("al"); break; }
                     if (ends("entli")) { r("ent"); break; }
                     if (ends("eli")) { r("e"); break; }
                     if (ends("ousli")) { r("ous"); break; }
                     break;
           case 'o': if (ends("ization")) { r("ize"); break; }
                     if (ends("ation")) { r("ate"); break; }
                     if (ends("ator")) { r("ate"); break; }
                     break;
           case 's': if (ends("alism")) { r("al"); break; }
                     if (ends("iveness")) { r("ive"); break; }
                     if (ends("fulness")) { r("ful"); break; }
                     if (ends("ousness")) { r("ous"); break; }
                     break;
           case 't': if (ends("aliti")) { r("al"); break; }
                     if (ends("iviti")) { r("ive"); break; }
                     if (ends("biliti")) { r("ble"); break; }
                     break;
           case 'g': if (ends("logi")) { r("log"); break; }
       } }
    
       /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
    
       private final void step4() { switch (b[k])
       {
           case 'e': if (ends("icate")) { r("ic"); break; }
                     if (ends("ative")) { r(""); break; }
                     if (ends("alize")) { r("al"); break; }
                     break;
           case 'i': if (ends("iciti")) { r("ic"); break; }
                     break;
           case 'l': if (ends("ical")) { r("ic"); break; }
                     if (ends("ful")) { r(""); break; }
                     break;
           case 's': if (ends("ness")) { r(""); break; }
                     break;
       } }
    
       /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
    
       private final void step5()
       {   if (k == 0) return; /* for Bug 1 */ switch (b[k-1])
           {  case 'a': if (ends("al")) break; return;
              case 'c': if (ends("ance")) break;
                        if (ends("ence")) break; return;
              case 'e': if (ends("er")) break; return;
              case 'i': if (ends("ic")) break; return;
              case 'l': if (ends("able")) break;
                        if (ends("ible")) break; return;
              case 'n': if (ends("ant")) break;
                        if (ends("ement")) break;
                        if (ends("ment")) break;
                        /* element etc. not stripped before the m */
                        if (ends("ent")) break; return;
              case 'o': if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
                                        /* j >= 0 fixes Bug 2 */
                        if (ends("ou")) break; return;
                        /* takes care of -ous */
              case 's': if (ends("ism")) break; return;
              case 't': if (ends("ate")) break;
                        if (ends("iti")) break; return;
              case 'u': if (ends("ous")) break; return;
              case 'v': if (ends("ive")) break; return;
              case 'z': if (ends("ize")) break; return;
              default: return;
           }
           if (m() > 1) k = j;
       }
    
       /* step6() removes a final -e if m() > 1. */
    
       private final void step6()
       {  j = k;
          if (b[k] == 'e')
          {  int a = m();
             if (a > 1 || a == 1 && !cvc(k-1)) k--;
          }
          if (b[k] == 'l' && doublec(k) && m() > 1) k--;
       }
    
       /** Stem the word placed into the Stemmer buffer through calls to add().
        * Returns true if the stemming process resulted in a word different
        * from the input.  You can retrieve the result with
        * getResultLength()/getResultBuffer() or toString().
        */
       public void stem()
       {  k = i - 1;
          if (k > 1) { step1(); step2(); step3(); step4(); step5(); step6(); }
          i_end = k+1; i = 0;
       }
    
       /** Test program for demonstrating the Stemmer.  It reads text from a
        * a list of files, stems each word, and writes the result to standard
        * output. Note that the word stemmed is expected to be in lower case:
        * forcing lower case must be done outside the Stemmer class.
        * Usage: Stemmer file-name file-name ...
        */
       public static void main(String[] args)
       {
          char[] w = new char[501];
          Stemmer s = new Stemmer();
          for (int i = 0; i < args.length; i++)
          try
          {
             FileInputStream in = new FileInputStream(args[i]);
    
             try
             { while(true)
    
               {  int ch = in.read();
                  if (Character.isLetter((char) ch))
                  {
                     int j = 0;
                     while(true)
                     {  ch = Character.toLowerCase((char) ch);
                        w[j] = (char) ch;
                        if (j < 500) j++;
                        ch = in.read();
                        if (!Character.isLetter((char) ch))
                        {
                           /* to test add(char ch) */
                           for (int c = 0; c < j; c++) s.add(w[c]);
    
                           /* or, to test add(char[] w, int j) */
                           /* s.add(w, j); */
    
                           s.stem();
                           {  String u;
    
                              /* and now, to test toString() : */
                              u = s.toString();
    
                              /* to test getResultBuffer(), getResultLength() : */
                              /* u = new String(s.getResultBuffer(), 0, s.getResultLength()); */
    
                              System.out.print(u);
                           }
                           break;
                        }
                     }
                  }
                  if (ch < 0) break;
                  System.out.print((char)ch);
               }
             }
             catch (IOException e)
             {  System.out.println("error reading " + args[i]);
                break;
             }
          }
          catch (FileNotFoundException e)
          {  System.out.println("file " + args[i] + " not found");
             break;
          }
       }
    }

